# Reactivity dollars notation?

1. Sep 10, 2009

### Smed

When writing a reactivity in dollars, what is the proper notation?

Would it be 0.43$or$0.43? or is it just 0.43?

Thanks,
Smed

2. Sep 10, 2009

### Staff: Mentor

I've seen it written as $0.43, which is the way I was taught. This example indicates 43 cents, of course. This more a term used in nuclear engineering, where "one dollar of reactivity is equivalent to the effective delayed neutron fraction, ßeff". If the reactivity of the core is one dollar, the reactor is prompt critical. More often I see the unity pcm. But then this book - Nuclear engineering: theory and technology of commercial nuclear power By Ronald Allen Knief has reactivity written as n$, where n is the value.

Slide 9 of this presentation - http://documents.epfl.ch/groups/l/lr/lrs-unit/www/Neutronics/Lesson%2013/NeutronicsCR-13Lectures.pdf [Broken]
has units 1$. I'd say go with 0.43$, but check with the instructor/professor.

Last edited by a moderator: May 4, 2017